President's Address. 63 



As the water in a stream increases in depth there is an increas- 

 ing variation in the velocity of the water at top and at the bottom. 

 The water near the surface cuts the banks and supplies itself with 

 silt in accordance with its carrying capacity determined by its ve- 

 locity. A stream twenty feet deep has a larger absolute amount of 

 water near the bottom flowing slowly than the same stream would 

 have when but five feet deep. The silt gathered from near the top 

 gradually works downward and on account of the slow- moving water 

 below silts up the bottom of the river much faster than would be 

 done if the stream were only half as deep. The filling done by one 

 flood simply helps the stream to overflow its banks the more read- 

 ily during subsequent floods, and therefore becomes a menace. 



As just stated, levees undoubtedly are serviceable and satisfactory 

 for mild floods. It is surprising, however, how many engineers, some 

 of them government engineers, overlook the fact that levees must 

 be inordinately high in order to accommodate all the water of great 

 floods. Suppose we should try to levee the Kansas river to hold it 

 within its banks during a flood equal tn the one of 1903. At Law- 

 rence the water was more than five miles in width with an average 

 depth of about five feet. The cross-section area, therefore, of the 

 flood-water was so great that levees would have to be built more 

 than ten times as high as is usually mentioned in order to provide 

 a channel which would contain all the water. According to news- 

 paper accounts one of the leading engineering firms of Kansas City 

 made surveys up the Kansas river beyond Lawrence and made a 

 report to a citizens' committee, who employed them, which report 

 in turn was sent to a government engineer. According to these 

 same newspaper accounts both the Kansas Citj^ engineers and the 

 government engineer advised building levees to a height only a 

 little greater than that to which the water rose, mind you, on the 

 supposition that it would protect the valley lands from flood-water 

 in the future, omitting entirely to.take into consideration the vast 

 amount of water spread out over the valley. They are said to have 

 estimated that such a system of levees could be built for about $14,- 

 000 per mile on each side of the river. It cannot be believed that 

 engineers of the reputation of the ones referred to ever would sub- 

 scribe to such a fallacious doctrine. The influence on the public 

 mind, however, has been wrought and the unscientific landowner 

 situated in the river valley is likely to believe that the newspaper 

 accounts are correct, and that therefore such a system of levees 

 should be built. 



It should be noted here also that the tendency of the stream to 



